Diamond wire equipped with improved cutting bushes for cutting stone material

ABSTRACT

A diamond wire ( 1 ) is disclosed for cutting stone material comprising a support cable ( 2 ) with around it a plurality of cutting bushes ( 3 ) and a plurality of elastic means ( 5 ). The cuttting bushes ( 3 ) comprise: an hollow cylindric support ( 10 ); at least one diamond cutting sector ( 12 ) connected to an external surface of the support ( 10 ); and at least one non-diamond support/cutting sector ( 14 ) connected to the external surface of the support ( 10 ) and laterally connected to the cutting sector ( 12 ).

The present invention refers to a diamond wire equipped with improvedcutting bushes for cutting stone material.

Diamond wires are known in the art for cutting stone materials, suchwires using a plurality of cutting sectors made of diamond powders,mutually interconnected by elastic means such as springs or rubberbushes.

These diamond wires are costly, and the majority of their price iscomposed of the diamond cutting sectors themselves. Due to this veryreason, such wires also have the problem of their repair and their newlinings, since they, after a certain period of work, are sent back tothe manufacturer so that he can restore the worn parts, because theirhigh cost does not allow to discard them at least until when they arecompletely unusable. This obviously brings about a further waste ofcosts and times, both for the manufacturer and for the end user.

U.S. Pat. No. 4,097,246 discloses a method of making an abrasive wirefor sawing stone having a set of support members for respective cuttingmembers.

GB-A-723 197 discloses a stone-cutting cable saw having a set of singlesupport members for respective cutting members.

U.S. Pat. No. 3,598,101 discloses a wire saw similar to the onedisclosed in GB-A-723 197.

EP-A-0 213 434 discloses a diamond pin with a plurality of supportmembers for cutting members.

Patent Abstracts of Japan, vol. 013, no. 420 discloses a cutting deviceof diamond wire saw with a set of cylindrical cutting memberssurrounding respective cylindrical support members.

DE-A-195 16 999 discloses a diamond saw with an elongated support forcutting members.

Object of the present invention is solving the above prior-art problems,by providing a diamond wire equipped with improved cutting bushes whosecost is very low with respect to the original bushes and that guaranteea very satisfactory cutting efficiency.

A further object of the present invention is providing a diamond wirethat does without the problem of repairs and new linings, since thiswire is of such a low cost that it can be discarded after it worns outand can be replaced by a quite new one with a lower cost than the costof previous repair operations and the like.

The above and other objects and advantages of the invention, as willappear from the following description, are obtained by a cutting bushand a diamond wire containing such bush as claimed, respectively, inclaims 1 and 11. Preferred embodiments and non-trivial variations of thepresent invention are claimed in the dependent claims.

The present invention will be better described by some preferredembodiments thereof, given as a non-limiting example, with reference tothe enclosed drawings, in which:

FIG. 1 is a side partially-sectioned view of an embodiment of thediamond wire according to the present invention;

FIG. 2 is a side sectional view of an embodiment of a cutting bushaccording to the present invention; and

FIG. 3 is a top view of the bush in FIG. 2.

With reference to the Figures, an illustrative and non-limitingembodiment of the diamond wire 1 and of the cutting bush 3 of thepresent invention is disclosed.

As regards the diamond wire 1 for cutting stone material of theinvention, partially shown in FIG. 1, it substantially comprises asupport cable 2 (preferably made of steel) that is inserted inside aplurality of cutting bushes 3 of an improved type, that will bedescribed in detail below.

Function of the cable 2 is supporting and holding the bushes 3 for thefollowing cutting operations. For this purpose, the diamond wire 1 alsoprovides a plurality of elastic means 5 that interconnect one of thecutting bushes 3 to the next cutting bush 3: the elastic means 5 arealso placed around the support cable 2 and are preferably realised assmall pipes of plastic/rubber or springs, to make the work of the bushes3 easier when cutting. Other preferred embodiments of the elastic means5 are composed of small pipes made of plastic/rubber inside whichsprings are inserted.

As regards in particular the cutting bush 3 of the invention to beapplied on a diamond wire 1, it comprises:

-   an hollow cylindric support 10 adapted to house the support cable 2    of the diamond wire 1;-   at least one diamond cutting sector 12 connected to the external    surface of the support 10 through a process that will be described    below; and-   at least one non-diamond support/cutting sector 14 connected to the    external surface of the support 10 and laterally connected to the    cutting sector 12.

The connection of the support/cutting sector 14 to the support 10 canoccur through known means, or the sector 14 and the support 10 can berealised in a single body of the same material, for example metal, andin particular steel. The support/cutting sector 14 could also berealised in an harder material than the material of the support 10, suchas for example sintered tungsten carbide, or a sintered ceramic materialand not only a metallic material.

The arrangement shown in FIG. 2 is the preferred and most used one, inwhich the bush 3 is equipped in a sequence with a diamond cutting sector12 and a non-diamond support/cutting sector 14, that both cooperate forcutting the stone material. Moreover, the support/cutting sector 14 alsoperforms the function of supporting the cutting sector 12 itself, due tothe surface in which they are in mutual contact.

Other arrangements of the bush 3 are obviously possible according toapplications, such as for example the one in which the bush 3 isequipped in a sequence with a diamond cutting sector 12, with anon-diamond support/cutting sector 14 and with a diamond cutting sector12, or other equivalent arrangements.

With the cutting bush 3 as shown above, a ratio is realised between theworking cutting length of the cutting sectors 12 and the working cuttinglength of the support/cutting sectors 14 that ranges between 99:1 and20:80, and preferably between 70:30 and 30:70, and most preferably isequal to 50:50.

While in the main embodiment of the bush 3 the diameter of the sectors12 along the cutting direction is equal to the diameter of the sectors14, according to another possible embodiment, the diameter of thecutting sectors 12 is instead greater than the diameter of thesupport/cutting sectors 14, so that the cutting sectors 12 project for asmall distance along the cutting direction of the diamond wire 1, inorder to allow an operating easiness when cutting is started, providinga sort of starting element therefor.

As regards the results that can be obtained with the present invention,it has been found that, as pertains the cutting efficiency, thefrequency of the bushes 3 placed on the wire 1 is more meaningful thantheir length. It has in fact been proven that a diamond wire at 40pearls/m has a 100% efficiency, while the same wire at 37 pearls/m, withtherefore a 7.5% reduction of its diamond part, is able to reach a 70%efficiency with a value that is lower by 30% only. It has therefore beenthought to increase the frequency of pearls and to decrease the diamondpart. The obtained results confirmed the starting hypothesis. A wirewith 24 pearls/m has also been tested with bushes that were 9 mm long(corresponding for the diamond part to a wire with 37 pearls/m withbushes of a length equal to 6 mm) that had an efficiency that was by 25%lower than a wire with 30 pearls/m with bushes with a length of 6 mm.

As regards the process for realising the cutting bush 3, it comprisesthe creation of the cylindric cutting sector 12 using diamond powdersthat are sintered and simultaneously welded and linked to the support10; then a brazing step is possibly performed to improve the link withthe support/cutting sector 14. An improved cutting bush 3 is therebyrealised with a very low cost with respect to the previously-knownbushes, since the costly cutting sector 12 is much smaller than theprevious ones, anyway keeping a very satisfactory cutting capability.

1. Cutting bush for a diamond wire for cutting stone material,comprising: a hollow cylindric support configured to house a supportcable of said diamond wire; at least one diamond cutting sectorconnected to an external surface of said support; and at least onenon-diamond support sector connected to the external surface of saidsupport and laterally connected to said at least one cutting sector;wherein said at least one non-diamond support sector is connected tosaid at least one cutting sector to also perform a cutting of stonematerial, said non-diamond support sector operating as a non-diamondsupport/cutting sector, and wherein a material of which said at leastone support/cutting sector is composed is harder than a material ofwhich said support is composed.
 2. The cutting bush according to claim1, wherein said at least one support/cutting sector is made of asintered ceramic material.
 3. The cutting bush according to claim 1,wherein said at least one support/cutting sector is made of sinteredtungsten carbide.
 4. The cutting bush according to claim 1, furthercomprising: a second diamond cutting sector and a second non-diamondsupport/cutting sector disposed on the external surface of the support asequence with the at least one diamond cutting sector and the at leastone non-diamond support/cutting sector.
 5. The cutting bush according toclaim 1, further comprising: another diamond cutting sector in asequence with the at least one diamond cutting sector, and the at leastone non-diamond support/cutting sector.
 6. The cutting bush according toclaim 1, wherein said cutting sectors are made of diamond powders. 7.The cutting bush according to claim 1, wherein a ratio between a workinglength of the cutting sectors, and a working length of thesupport/cutting sectors ranges between 99:1 and 20:80.
 8. The cuttingbush according to claim 7, wherein the ratio between the working lengthof the cutting sectors and the working length of the support/cuttingsectors ranges between 70:30 and 30:70.
 9. The cutting bush according toclaim 8, wherein the ratio between the working length of the cuttingsectors and the working length of the support/cutting sectors is equalto 50:50.
 10. The bush according to claim 1, wherein the hollowcylindric support and the at least one-non-diamond support sector are asingle body of the same material.
 11. The bush according to claim 1,wherein a diameter of said cutting sectors is equal to a diameter ofsaid support/cutting sectors.
 12. The bush according to claim 1, whereinthe at least one diamond cutting sector is made of a sintered diamondpowder.
 13. The bush according to claim 12, wherein the at least onediamond cutting sector is simultaneous welded and linked to the hollowcylindric support.
 14. The bush according to claim 13, wherein the atleast one non-diamond support sector is brazed.
 15. The cutting bushaccording to claim 1, wherein a diameter of said cutting sectors isgreater than a diameter of said support/cutting sectors, said cuttingsectors projecting along a cutting direction for a greater extent thansaid support/cutting sectors.
 16. A diamond wire for cutting stonematerial, comprising: a support cable; a plurality of cutting bushesaccording to claim 1, said support cable being inserted inside saidcutting bushes for supporting said cutting brushes; and a plurality ofelastic means that interconnect one of said cutting bushes to a nextcutting bush, said elastic means being placed around said support cable.17. The diamond wire according to claim 16, wherein said elastic meansinclude small pipes made of plastic/rubber.
 18. The diamond wireaccording to claim 16, wherein said elastic means include springs. 19.The diamond wire according to claim 16, wherein said elastic meansinclude small pipes made of plastic/rubber inside which springs areinserted.